LibCrypt: Add LibCrypt, crypt, and crypt_r

Author: https://github.com/petelliott
Commit: 9dcbb263f1
Pull-request: https://github.com/SerenityOS/serenity/pull/2879
Issue: https://github.com/SerenityOS/serenity/issues/1168
Reviewed-by: https://github.com/BenWiederhake
Reviewed-by: https://github.com/awesomekling

Libraries/LibC/unistd.h

@@ -179,4 +179,12 @@ enum {
 };
 long sysconf(int name);
 
+struct crypt_data {
+    int initialized;
+    char result[65];
+};
+
+char* crypt(const char* key, const char* salt);
+char* crypt_r(const char* key, const char* salt, struct crypt_data* data);
+
 __END_DECLS